I don't know if anyone can explain why, but it has come up in the past that too strong a signal can cause problems.

Some people have reported such here, but their signal strengths were 100%, possibly even hotter. It was suggested to those users that they attenuate their signal, which subsequently helped with the problem.

I would say if you don't have any problems, don't worry about it, but keep an eye out.
It won't hurt anything if you try this, you can just undo it. It's really not something the cable company has to do, you can do it yourself if you are concerned about a service charge from the cable co.
You can buy the attenuator, from say Amazon, and install it on the cable going to the Tivo.